Muscles for the abdomen, front, and arm

Action for Pectoralis Major

Prime mover of arm flexion; adducts and medially rotates arm at glenohumeral joint

Action for Pectoralis Minor

Protracts and depresses scapula. Is contracted when you’re hunched over

Action for Serratus Anterior

Prime mover in scapular protraction, stabilizes and superiorly rotates scapula

Action for Rectus Abdominis

Flexes vertebral column, and compresses the abdominal wall

Action for Transverse Abdominis

Body’s natural back brace — compresses abdomen, supports spine while lifting

Action for External and Internal Oblique

Both contract and compress abdomen and flex the vertebral column. When one side contracts — lateral trunk flexion and/or trunk rotation results

Action for Diaphragm

Inhalation — contracts and flattens diaphragm to pull lung inferiorly and compress abdominopelvic cavity

Action for Internal Intercostals

Forceful exhalation — depresses ribs. Used in coughing or sneezing

Action for External Intercostals

Restful breathing — elevates ribs up and out, Exhalation — muscles relax allowing the elastic recoil of lung tissue